Arctic sea ice melt slows a bit in July
July 20th, 2010The National Snow and Ice Data Center (NSIDC) reports the rate of ice loss in the Arctic slowed in the first half of July, primarily because of a change in atmospheric circulation as the dipole anomaly, an atmospheric pattern that dominated the Arctic in June, broke down.
The report explains:
Through much of May and June, high pressure dominated the Beaufort Sea with low pressure over Siberia. Winds associated with this pattern, known as the dipole anomaly, helped speed up ice loss by pushing ice away from the coast and promoting melt.
However, the dipole anomaly pattern broke down in early July. In the first half of July, cyclones (low pressure systems) generated over northern Eurasia tracked eastward along the Siberian coast and then into the central Arctic Ocean, where they tend to stall. This cyclone pattern is quite common in summer. The low-pressure cells have brought cooler and cloudier conditions over the Arctic Ocean. They have also promoted a cyclonic (anticlockwise) sea ice motion, which acts to spread the existing ice over a larger area. All of these factors likely contributed to the slower rate of ice loss over the past few weeks.
In the last few days, high pressure has started to build again in the Beaufort Sea, but whether this will continue remains to be seen.
Still, Arctic sea ice extent at this time is the second lowest ever recorded, as seen in this chart from the Japan Aerospace Exploration Agency website, IJIS.
